X Ray Backscatter

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Nucsafe and Scatter X-ray Imaging are a trademarks of Nucsafe, Inc.Copyright © 2010 Nucsafe, Inc. All ri ghts reserved. 07/22/2010 | 1

BOEING is a trademark of Boeing Management Company.Copyright © 2010 Boeing. All rights reserved.

X-ray Backscatter Imaging for Aerospace Applications

Gary Georgeson, Talion Edwards, Jim Engel – Boeing Research & Technology

Dan Shedlock – Nucsafe Inc.



07/22/2010 | 2Copyright © 2010 Boeing and Nucsafe. All rights reserved.

X-ray Backscatter vs. Traditional X-ray

Transmission X-ray

Pros• Simple Equipment

• High resolution in favorable conditions

• Access to smal l areas

Cons• High radiation f ield

• Requires access to both s ides

• Large area coverage takes many shots

• Images require post processing for most

Backscatter X-ray

Pros• Automated Col lect ion

• Fast Data Collect ion / Real-time imaging

• Low radiation field

• Single sided process

• Large area images

Cons• System cost

• Physical size/complexity of system

• Resolut ion dependant on standoff

X-ray Image

Transmission

X-ray DetectorBackscatter

X-ray Detector

X-ray

TubeX-ray Tube

Rotating

Collimator




Example Image




System Description

• Scanning head consist of• x-ray tube• Illumination beam collimator• Detectors to measure the backscatter signal

• Can be adapted to use any X-ray energy• Energy required dependant on application

• Uses COTS X-ray tubes• Currently systems available from 160-225 kV

• Design of collimator and aperture• Can be pointed in different di rections• Tailoring of aperture size for different applications

• Configurable Detector Arrays• Different size detectors and detector combinationallow for easy customizations to applications

• May use Radiography by Selective Detection(RSD) to enhance image contrast and subsurfaceresolution

X-ray Backscatter Scanning Head




System Description (cont)

Mobile System

• The linear rail system is mobile and can be expanded toimage different lengths

• Designed to work in different or ientations (straight-up,

up-side-down)

• Modular to setup and move with 2 people

Robotic System

• X-ray backscatter imaging for any complex mot ion profile

• Allows end user customized mot ion

• Combines state-of-art off the shelf motion with x-ray

backscatter imaging

• Robotic System offers customized motion for each

application




Aerospace Operational Considerations - Portability

• Packaging design for use in and around aircraft

Compatibility with Ground Support Equipment Sized for ingress and egress

• Minimize Potential for FOD

• Portabil ity and Setup• Shipping size and Transportability

• High Voltage Connections

• Power Service Requirements


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Aerospace Operational Considerations - Automation

• Integration into manufacturing area

Availabil it y o f Shop Floor Space

Compatibility with Ground Support Equipment

• Motion programming

• Multiple DOF require additional safety planning

• Mounting provisions and power service


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Aerospace Operational Considerations (cont.)

• Safety to aircraft electronics

• FCC testing for EMI/EMR shielding• Affect of ionizing radiation on sensitive solid state electronics

• Radiation safety• Long exposure times required create the need to implement

mult iple layers of safety into deployable system• Occupational & nonoccupational exclusion zones

• Defeating perception of danger based on experience with

traditional transmission X-ray

• Challenge in measuring field strength of highly col limated

moving source with traditional field survey meters

• Other safety considerations

• Robotic mot ion hazards

• Ergonomics of handling, assembling and disassembling in

conf ined areas


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Application of X-ray Backscatter for Aircraft NDE

• Low z materials typical to aircraft sui ted to backscatter

• Many NDE inspections at known locations and depths

• Ability to image through multiple layers

• Continuous contact with nested layers not required as

with other NDE techniques



Contributors to Image Quality

• Speed – directly related to image quality by countingstatistics (inherence noise in the image)

• Standoff• Illumination pencil beam diverges from the x-ray source

• Backscatter signal decreases with a 1/R2

• Size and Weight – related to image quality at given

speeds• More intense x-ray sources (higher mA) require larger tubes,

generators and cooling capacity• Larger area detectors can increase capture of scatter

• Type of detector material



Affects of Standoff on Image Resolution

• Standoff is driver in spatial resolution of images

• At reduced standoff, edge definition is significantly improved, contrast hasincreased, and much smaller features can be resolved

150 mm Standoff 450 mm Standof f

5 mm/s 5 mm/s

100 mm/s100 mm/s



Affects of Standoff on Image Resolution (cont.)

SXI image at 150 mm standof f

SXI image at 450 mm standof f

• At 3x the standoff, contrast decrease by about 9%

• Resolut ion falls off with contrast as the standoff is increased.

• Statistical noise increased from 1.26% to 1.54% or increased by 20%.

• Statist ical noise increases with standoff follows Poisson count ing statistics

varying with the square root of the contrast intensity value.

• Resolut ion lost by standoff partially recoverable using smaller apertures

• Scan speed must be reduced by a factor proportional to the reduction

of the open area of aperture.

•Standoff is cr itical to application development

40

60

80

100

120

140

160

0 10 20 30 40 50 60 70 80

150 mm, 5 mms

450 mm, 5 mm/s

150 mm, 20 mm/s



X-Ray Backscatter NDE Applications

• Corrosion Detection

• FOD Detection• Fluid Intrusion

• Cracks and Defects



• Advantages of X-ray Backscatter Imaging• Ability to image large area from with single sided access

• Real time imaging allows recursive scanning

• Low radiation field allows smaller exclusion zones

• No continuous media required for second layer inspection

• Image based technique allows for easy interpretation

• Challenges to adoption of technique• Development of new standards/procedures

• High scan speeds require large equipment

• Limited available of tailored x-ray sources• Detailed depth information requires longer scans

• Site specific radiography requirements

Conclusions



Snakes on a Plane

Gary Georgeson, Joe Hafenrichter, Bill MotzerBoeing Research & Technology

Seattle, WA

NASA In-Space NDI WorkshopFebruary 29- March 1

Houston, TX



A

A

B

B

C

C

Planes have many difficult to access areas.



B” – B”

Snakes Can Move through Access Holes




Potential Fuselage Applications

A - ADepaint

Lap Joint &ScribelineInspection

Inspectionfor Corrosion

underGalleys and

Lavs

Inspection

for WireFault

Inspectionof Control

Cables

Inspection ofFasteners for

LightningStrike Damage

Inspectionof FloorBeams

Inspectionfor Keel

Corrosion

Inspection of

FrameCrack

InspectionBehind

Insulation

InspectionBehind

Lavs andGalleys

InspectionBehind

Equipment

Inspection ofClosedSection

Stringers




B” ’ – B” ’

Inspectionof Bonded

or Co-CuredJoints

Inspection of Bonded Joints

B” ’ – B” ’

PairedThrough

Transmission Inspectionof Bonded

Joints

PairedThrough

Transmission Inspectionof Bonded

Joints




B - B

Inspectionof IML

SandwichStructure

Inspection of Sandwich Panels

B - B

Paired ThroughTransmissionInspection of

SandwichStructure




Potential Wing and Fuel Tank Applications

CorrosionInhibitor

Application

LandingGear BayCorrosionInspection

Inspection of Sideof Body

Joint

ExteriorWash

InspectionunderFuel

Bladder

Limited AccessScarfing

LSP GridInspection

StringerInspection

PairedThrough

TransmissionInspection

(TTU, X-Ray,Other)

C - C

SwimmingSnake In-

TankInspection

SwimmingSnake

inspecting Pipesand Tubes




Inspectionof

LandingGear BayCracks

andCorrosion

Inspectionof

LandingGear

Cracks

Inspection ofLanding Gear

Doors

Landing Gear and Wheel Wells




Robotic Snakes are of interest to Boeing



07/22/2010 | 24

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